Current electricity Flashcards
Current (I)
The rate of flow of charge I= Q/t
Q= charge transferred
t=time
ammeter
A device that measures current. It must be connected to a series in a circuit
Define (A/C) and (D/C) current
dc flows in one direction
ac continunly changes direction
Voltage/Potential difference
the work done when 1 coulomb of charge is moved from one point to another
Electromotive force (emf)
The potential difference between terminals of a battery when no current is being drawn from the battery
Voltmeter
A device that measures potential difference across a component.
A voltmeter must be connected in parallel or across the component in a circuit
Resistance (R)
The ratio of voltage across it to the current flowing through it R=V/I
Ohm’s Law
The current flowing through a conductor is directly proportional to the potential difference across is, if the temperature remains constant
Resistivity
The resistance of a cube of side 1m of the material
Joule’s Law
the rate of heat produced in a conductor is proportional to the square of the current flowing through it
Electrolysis
the passing of an electric current through a liquid causing a chemical reaction
Semiconductor
A substance whose resistivity is between that of a good conduct and a good insulator. The resistivity decreases as the temperature increases
doping
The addition of impurities to a semiconductor to increase its conductivity
Thermistor
A semiconductor whose resistance decreases as temperature increases
